• Journal of the Korean Chemical Society
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• v.26 no.1
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• pp.36-42
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• 1982

Filters were evaluated to use in the collection of ammonia and ammonium salts in the atmosphere. Ammonia from standard gas generator was collected on a glass fiber filter impregnated with a mixture of 3% boric acid and 25% glycerin. The collection efficiency by the impregnated filter was 96.4${\pm}$2.15% in pH control method and 97.4${\pm}$1.06% in the atmosphere for five measurements, respectively. Adsorption and desorption of gaseous ammonia were compared using three commercially available filters; glass fiber, quartz fiber and polycarbonate filters. Both glass and quartz fiber filters indicated some loss of ammonium salts and adsorption of ammonia, respectively. However, polycarbonate filter was found to be satisfactory for the collection of ammonium salts in the atmosphere. The minimum measurable concentration of ammonia was 0.83ppb (ca. 0.63${\mu}g$/$m^3$) by spectrophotometry of the indophenol method for the sample collected by 47mm${\phi}$ filter(20l/min, 60min). The sensitivity of the present method is about 20 folds higher than that of conventional method of bubbler collection followed by spectrophotometry, so that this method makes it possible to measure thevariation of ammoniacal concentrations in the atmosphere for a short time period of about 60 min.

• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.293-299
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• 1998

An objective of this study is to develop a voltage measuring device that uses a gas-filled switch (GS) on 22.9 kV-y extra-high voltage distribution lines. The voltage measuring device proposed in this paper is a kind of capacitive divider which consists of a detecting electrode attached outside of the bushing of GS, an impedance matching circuit, and a voltage buffer. It can be easily installed in an established GS without changing the structure. For the calibration and application investigations, the voltage measuring device was set up in the 25.8 kV 400 A GS, and a step pulse generator having 5 ns rise time is used. As a result, it was found that the frequency bandwidth of the voltage measuring device ranges from 1.35 Hz to about 13 MHz. The error of voltage dividing ratio which is evaluated by the commercial frequency voltage of 60 Hz was less than 0.2%. In addition, voltage dividing ratio in the commercial frequency voltage and in a non-oscillating impulse voltage were compared, and their deviation were less than 0.7%.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.166.2-166.2
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• 2016

최근 생산 장비의 발달로 인해 절삭공구, 전기전자 부품, 항공 및 자동차 부품 생산에 필요한 생산 장비의 수명연장, 고속 절단 및 고성능화가 중요시 되면서 우수한 내구성, 내마모성 및 고온 안정성을 갖는 기계부품 및 공구를 요구하게 되었다. 내마모성을 가지는 표면을 얻기 위해서는 TiN, TiC, AlN, Al2O3, CrN, ZrO2와 같은 경도 높은 물질을 증착하여 특성을 개선시키는 방법이 있다. 특히 AlN은 비교적 우수한 경도와 고온 안정성을 가지고 있어, 생산 장비의 고속 절단 및 반복되는 정밀 작업으로 인한 열충격과 마모를 완화시키는 역할을 하는 코팅재로 사용하기 적합하다. 본 실험에서는 RF-magnetron sputtering 방법을 이용하여 AlN 박막을 파워 150W, 질소가스 분압비에 따라 25%, 50%, 75%, 100%의 조건으로 금속기판 위에 증착하였다. 금속 기판 위에 제작된 AlN막은 XRD (X-ray Diffraction)을 사용하여 배향성을 확인하였고, HM-220 (Micro-vickers hardness tester)을 사용하여 AlN박막의 경도를 측정하였으며, SEM (Scanning Electron Microscope), AFM (Atomic Force Microscope)을 이용하여 표면의 구조와 거칠기를 측정하였다. 이 실험을 통하여 우수한 물성과, 치밀한 조직의 AlN박막이 고속 절삭 공구, 유공압 실린더, 베어링과 같은 금속부품의 코팅소재로 적용가능 할 것으로 기대된다.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.4
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• pp.401-410
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• 2016

Since the late 19th century, scientific logic and techniques have been used extensively in the field of clinical pathology, including many laboratory tests utilizing various apparatuses and instruments. Among the techniques to measure hemoglobin, the visual color comparison method was most popular around this time; the specific gravity method and gasometric method were not widely adopted. Instruments that use the visual color comparison method include Gowers' hemoglobinometer, von Fleischl's hemoglobinometer, Dare's hemoglobinometer, Oliver's hemoglobinometer, Haden-Hausser hemoglobinometer, and Spencer Hb meter. Initially, the visual color comparison methods were used to diluate and hemolyze blood with distilled water and then to measure its color. Later, these methods were further developed to measure hemoglobin without dilution, and improved with the formation of acid or alkaline hematin ensuring the stability of color development. Hammerschlag's method as well as the Schmaltz and Peiper's methods were based on specific gravity measurement, but they were not widely used. The gasometric method used the Van Slyke gasometer, indirectly measuring the hemoglobin concentration. This method provides the most accurate results. This survey examined the characteristics and limitations of hemoglobinometers and methods used to measure hemoglobin from the late 19th century to the early-and mid-20th century. Moreover, this study aims to improve the understanding and applicability of the current methods and emerging technologies used in measuring hemoglobin. It is also expected that this investigation is the starting point to promote awareness of the need to organize historical data for a variety of historical relics of the diagnostic laboratory tests.

• Analytical Science and Technology
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• v.16 no.3
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• pp.218-225
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• 2003

Hydrogen Chloride is among the most problematic gases used in semiconductor process. It raises serious environmental and health problems due to its extreme toxicity. This study is to develop a method to effectively remove hydrogen chloride gas during the process by using various types of inorganic gas adsorption agents, which have not been attempted in the conventional methods. The removal efficiency of the gas was both qualitatively and quantitatively measured by a FT-IR spectrophotometer. The whole device for the measurement has been designed and built in our lab. The removal efficiencies of hydrogen chloride gas were compared between those tested resins; zeolite A, modified AgA zeolite, ZnO, and $AgMnO_3$. The experimental result revealed that ZnO showed the best efficiency that had removed 0.067 g of HCl per 1 g of the resin used.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.155-158
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• 2005

산업현장에서 많이 사용되고 있는 전력기기에 결함이 발생하면 치명적인 사고로 진전되어 경제적, 인적 손실이 발생될 수가 있다. 본 논문은 GIS에 사용되는 절연가스인 $SF_6$의 압력 변화에 따른 부분 방전을 모의하고, 발생되는 부분방전 신호를 절연 진단 방법 중 하나인 UHF법을 이용하여 부분방전 시 방사되는 방사전자파의 스펙트럼을 분석해 금속이물질이 $SF_6$가스 부분방전에 미치는 영향을 측정하였다. 이러한 연구는 현장 GIS 및 $SF_6$ 가스절연 전력설비에서 내부압력 변화 시 금속이물질에 의해 발생되는 절연파괴 사고의 방지에 중요한 역할을 할 것으로 사료된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.217-220
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• 2010

This paper presents an achieving method of reducing maximum acceleration for the missile by decrease of burst pressure in a nozzle closure. The relation of notch shape and burst pressure for a nozzle closure is examined by experiment. In the point of maximum acceleration reduction for a missile, an improved nozzle closure effects well compared with that of a reference closure by ground burning test of a gas generator.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.19.2-19.2
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• 2009

ITO는 n형 반도체 특성을 가지며 이와 동시에 높은 가시광투과율과 낮은 전기전도도를 가짐으로써 다양한 투명전극소재와 가스 검출센서로 많이 활용되고 있다. 본 연구에서는 RF magnetron sputtering 법을 이용하여 상온에서 glass 기판 위에 두께 100nm로 ITO 그리고 하층 ITO 박막 (두께 50 nm) 위에 층간 금속 (두께 5 nm)을 증착하고 다시 상부 ITO 박막 (두께 45 nm)을 증착하여 3층의 적층형 박막센서를 제작하였다. 층간 금속으로는 Au와 Cu를 각각 사용하였다. 박막 증착 후엔 진공분위기에서 $150^{\circ}C$, $300^{\circ}C$로 열처리 과정을 거쳐 열처리 전후의 물성 및 감지특성을 비교해보았다. 분석방법으로는 XRD, SEM, AFM, Hall effect 장치 등을 이용하였다. 분석 결과 $300^{\circ}C$에서 진공 열처리한 ITO/Au/ITO(IAI) 박막센서가 높은 결정화도 와 전기적 특성이 나타났으며, 0 에서 1000ppm 까지의 메탄가스의 민감도 측정에서도 열처리된 IAI 박막센서가 기존의 ITO 박막센서보다도 약 70% 정도 향상된 민감도를 나타내었다.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.262-269
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• 2008

The residual gas analyzer (RGA) is employed for the process control of a vacuum system by measuring residual gases in it. This review paper introduces operating principles of the RGA and problems that can be encountered during use, together with their possible solutions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.10-10
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• 1999

선형 및 비선형 GPA 기법을 이용한 가스터빈 엔진의 성능예측 및 진단을 연구하고 전형적 산업용 가스터빈 엔진인 TB5000에 적용하여 최적의 계측변수를 정의하였다. 선형 GPA는 가스가 지나가는 구성품의 계측가능한 온도, 압력, 연료유량, 로터 회전수 등과 같은 종속변수와 효율, 유량과 같은 측정불가능한 독립변수의 관계 방정식을 열역학 법칙, 연속방정식, 질량 및 에너지 보존법칙, 구성품 성능곡선 등으로부터 유도하는 것이며 비선형 GPA는 독립변수와 종속변수의 비선형 관계를 충분히 고려하기 위해 선형 GPA를 반복적으로 적용하는 방법이다. 본 연구에서 반복기법은 Newton-Raphson 반복기법을 사용하였다.